Circuit interrupter



Patented Sept. 1, 1942 2,294,2201 cmoorr m'rsaaurraa Herbert L. Rawlins,Wilkinsburg, Pa., minor to Westinghouse Electric is ManufacturingCompany, East Pittsburgh, Pa., a corporation of Pennsylvania ApplicationMay 25, 1938, Serial No. 209,969

27 Claims. (Cl. 200-149) This invention relates to circuit interruptersand more particularly to circuit interrupters of the air break type.

It is an object of my invention to provide a circuit interrupter capableof interrupting high voltage, high current arcs in air or gas withoutrecourse to oil or other liquid arc extinguishing media.

A more specific object of my invention is to provide a circuitinterrupter in which are extinction is accomplished by compelling theestablished arc to operate in a narrow channel or slot between walls ofinsulating material.

Another object of the invention is the provision of an improved arcextinguishing structure for circuit interrupters of the expulsion type.

A further object of my invention is to improve the arc extinguishingability of narrow slot type interrupters by the provision of gasgenerating materials adjacent the arc path so as to provide a flow ofarc extinguishing gas through the arc stream.

Other objects and advantages relate to improvements in the structuralarrangement of my circuit interrupter whereby a more eilicientutilization of the products of decomposition of the arc is obtainedduring the circuit interrupting operation, and will appear more fully inthe following description when read in connection with the accompanyingdrawings, in which:

Figure l is a side elevation view, partially in section, showing anembodiment of my invention;

Fig. 2 is a cross-sectional view taken along the line II--II oi Fig. 1;

Fi 3 is a sectional view of one of the interrupting units of my circuitinterrupter showing the contacts in the open position;

Fig. 4 is a sectional view of a modified form of circuit interrupter;

Fig. 5 is a sectional view of another form of circuit interrupter:

Fig. 6 is an elevation view of a modified filling member or plungerwhich may be utilized in any of the foregoing circuit interrupters;

Fig. 7 is a sectional view of still another form of filling member whichmay be used in conjunction with the above-identified interrupters,

and

Fig. 8 is a sectional view of stillanother form of circuit interrupterembodying the principles of my invention.

Referring to the drawings, and particularly to Figure l, the referencecharacter 'lll designates a base, preferably of insulating material,which supports two are extinguishing units generally designated at I2,the right hand unit being shown in vertical section. Each unit l2comprises a tubular member it of insulating material which is open atboth ends and has its lower end screwthreaded into the base Ill and itsupper end screw-threaded for the reception of a collar or cylindericalmember ii. The upper end of the collar I6 is partially closed by anannular plate 18, preferably of conducting material. The inner surfaceof the annular plate I8 is threaded for the reception of a cylindricalclosure cap member 28 also of conducting material which is open at itslower end end closed at its upper end and has an internal diametersubstantially the same as the diameter of the tubular member ll. Thelower endof the cap member 28 is provided with an annular recess 22 inwhich a tubular fixed contact member 24 is positioned. The contactmember 24 may be provided with a plurality of segmental contact sections28 adapted to engage and cooperate with a movable tubular contact 28extending through the bore of tubular member H and substantially fillingthe same. The tubular contacts 28 of the two circuit interrupting unitsI2 are supported from opposite ends of a metallic bridging. bar 30. Thebridging bar 38 may be actuated by an operating rod 32 coupled theretoas shown by any suitable operating mechanism not illustrated.

When the circuit interrupter is in the closed position as shown in Fig.1, the circuit therethrough proceeds from a terminal 34 secured to thecap member 20, through the cap member 20' to the contact member 22,contacts 26, movable contact 28 to the bridging bar 38 from whence thiscircuit continues through the left hand interrupting unit l2 in asimilar manner as previously described and emerges at the other lineterminal 86. From the foregoing description it is apparent that as thebridging bar 30 is moved downwardly during conditions of load, an arcwill be drawn between the fixed contacts 26 and the movable tubularcontacts 28. As the two tubular contacts move through their respectivetubular member It, an arc will be drawn therein. In order to provide foruniform erosion of the inner walls of the tubular member l4, and alsothe exposed contact surfaces of both the fixed and movable contacts, Ihave provided an annular coil 38 disposed within the collar IS, theupper end of which is connected to the annular plate member 18 and thelower end of which is connected to an annular arcing plate 40.

The inner surface of the coil i8 is protected from the action of thearcby an annular member when thus energized, produces a radial magneticfield across the are space for rotating the arc therearound. Arcextinction in this instance is rendered more effective by compelling thearc to operate in a narrow slot or passage. The narrow are passage isprovided between the tubular member l4 and a movable plunger member 44of insulating material, preferably supported by and movable with thetubular contact 28 and bridging bar 80. For example, the plunger 44 maybe secured at its lower end to a rod 48 which in turn is supported atits lower end by a transverse bolt 48 in fixed relation with respect tothe bridging member 80.

The support rod 46 is preferably held centrally of the tubular contact28 by means of a spider 58 which may be secured to the movable contact28 by screws as shown. The plunger 44 has its lower end tapered andextends partially into the tubular contact 28, thereby providing anannular passage as shown at 52 between the upper edge of the contact 28and the plunger. The plunger 44 also has such a diameter that when it ismoved into the tubular member l4 an annular arc passage is provided ofrestricted cross section.

I have found that effective are extinction may be obtained with an arcpassage width of from /5 to y The requirement for a particular arepassage width, however, depends to some extent upon the materials usedfor the plunger 44 and the tubular member l4. In the event of the use ofrefractory or non-gas evolving materials, a much smaller arc passagewidth is recommended than if either the plunger 44 or the tubular memberI4 is composed of gasevolving insulating material. If non-gas evolvingor refractory materials are used in forming the tubular member l4 andthe plunger 44, are extinction is accomplished in accordance with thedeionization theory set forth in J. Slepian Patent No.1,836,994, issuedDec. 15, 1931, in which deionization of the arc stream is accomplishedby compelling the arc to operate in the narrow channel or passage. Inthis instance a narrow passage is provided between the tubular member [4and the plunger 44. Under such conditions rapid deionization takes placeso that when the arc passes through current zero, the space between theseparating contacts in the constricted passage has been so completelydeionized that the arc will not restrike when the voltage again buildsup in the opposite direction.

Any products of decomposition resulting from the action of the are uponthe wall members of the annular passage will have free flow from thepassage through the annular opening 52 and through the passage of thetubular contact 28.

I have found that are extinction may be facilitated by making either thetubular members H or the plunger members 44, or both the tubular membersand plunger members of insulating material which evolves considerablequantities of gas when acted upon by an arc. When such gas evolvingmaterials are used to define the walls of the annular arc passage, it isapparent that due to the constricted nature of such passage an are drawnbetween the fixed contacts 26 and the moving contact 28 will intimately'contact the passage walls so as to produce considerable quantities ofarc extinguishing gas. Inasmuch as the upper end of the arcextinguishing structure is completely closed by the cylindrical capmember 28, the only escape for the gas from the arc passage is throughthe annular opening 82. It will be observed that in passing through thisopening the gas must flow over the upper surface of the tubular movingcontact 28, and in so doing must pass through the arc stream. The fiowof gas directed in this manner greatly facilitates arc extinction. Theimproved performance of the interrupter occasioned by the use of gasevolving material in the construction of the tubular member l4 and theplunger member 44 may be further explained as follows. The blast of gasgenerated by the heat of the are upon the members of insulating materialis projected more violently upon a section of the are extending acrossthe annular exhaust opening 52 and thus tends to destroy the continuityof the are at that point. As long as a high degree of ionizationpersists in the arc stream, there is a strong tendency for the arc tomaintain its continuity and the blast of gas will substantiallycompletely flow around the arc and through the exhaust opening withoutappreciably deionizing the arc stream which is necessary to bring aboutare extinction. It is only as the ionization decreases with decay ofcurrent as the arc current approaches zero that a gas blast canpenetrate the arc stream and remove the ionized gas particles withsufficient rapidity to bring about are extinction. The period duringwhich are extinction is normally made possible is necessariLv short andcorresponds to a very short time interval in the region of a currentzero.

If the-arc stream is caused to play against a refractory or non-gasforming surface and the blast of gas is caused to stream over thesurface, greater diificulty is experienced in bringing about areextinction than if the surface is composed of gas forming material.

The reason for this diflerence in performance may be explained asfollows. In case of the nongas forming surface a finite layer of gas ofzero velocity is caused to form between the surface of the non-gasforming material and the moving stream of gas. This layer of immovablegas in the presence of an arc is highly ionized and tends to maintainthe continuity of the arc until substantially a current zero. The timeduring which low ionization exists and during which the blast maypenetrate the arc stream may, however, be so short that the arc streamis not sufficiently deionized to bring about are extinction. If, on theother hand, the surface against which the arc plays is formed of gasproducing material, the heat of the arc generates gas which sets upturbulence in the presence of a blast of gas streaming past the surfaceand thereby prevents the formation of an immovable layer of highlyionized gas adjacent to the surface. Thus the gas blast is permitted topenetrate the arc stream much earlier in the current cycle preceding acurrent zero and consequently permits a more rapid removal of theionized particles from the arc stream.

I have also discovered that it is desirable to provide a housing 54 onthe lower side of the base plate l0 for the purpose of providing a gasreceiving chamber 56. The housing 54 also serves the purpose ofprotecting the moving contacts 28 on the bridging member 30 as well asany other parts of the operating mechanism which may be housed therein.The gas which is discharged through the tubular contacts 28 is thuscollected within the chamber 56 where it is cooled and .deionized priorto its escape to the atmosphere through a suitable escape valve 58. Thusthe hot or partially ionized gases are and somewhat less separation.

prevented from being discharged adjacent line terminals which mayotherwise produce i'lashover and breakdown of the insulating surfaces ofthe interrupter. 1

I have also discovered that somewhat improved results can be obtained,by using a plunger 88 as shown in Pig. 8. having circumferential groovesor channels 82 therein instead of the smooth faced plunger 44 previouslydescribed. The improved operation is believed to be achieved in that thegroves or channels 82 provide a storage space for gas during the highvalues of instantaneous current under which conditionthe pressures inthearcpassageareat a maximum. As the instantaneous value of arc. currentapproaches zero, the pressure in the arc passage decreases, therebyallowing the gas stored.

within the channels 82 to fiow into the arc passage through the arcstream and to be expelled through the tubular contact 28. In otherwords, the channels 82 act as a storage reservoir for the storage of gasat time intervals when large quantities of gas are generated andprovides means for delivery of gas through the arc stream. as the arccurrent approaches zero, at which time a larger flow of gas is needed tocompletely deionize the arc stream.

I have also discovered that somewhat improved results may be obtained byproviding pockets or grooves along the outside walls of the aaoaaor the,

18, more gas is generated by the action of the hot gases on theseplates. The net result is the formation of a larger quantity ofrelatively cooler gas since the process of decomposition removes areassage by means of a structure as shown in Fig. 4. In the arrangementshownin Fig. 4, the tubular member I has been replaced by a structurecomprising a plurality of plates it having alined openings therethroughof slightly larger diameter than the outside diameter of the tubularcontact 28. The plates 84 are preferably held in spaced relation withrespect to each other by annular spacing members. 88, and are clampedbetween two end plate members 88 and 18. The upper plate member 18supports the cylindrical cap member 28. fixed contacts 28 and annulararcing plate 48, and a radial field coil 88 of construction similar tothat described in connection with Fig. 1.

From the illustration in Fig. 4, it is apparent that the spacing members88 between the plates 84 provide annular pockets or storage chambers 12adjacent the arc passage. The improved results obtained with thearrangement shown in Fig. 4 is attributed to the greater gas storagecapacity of the chamber 12, and also due to the fact that the plates 64present considerable surface area to the gas stored therebetween,thereby cooling the gas to a considerable extent. This cooling eflect isbeneficial in producing a more rapid deionization of the arc stream.

I have also discovered that the gases maybe cooled by use of annularmetallic-plates preferably of copper disposed in the chambers I2 betweenspacing members 14 as shown. More effective are extinction may, however,be obtained by the use of a larger number of plates of gas evolvinginsulating material adjacent the arc passage u shown in Fig. 5. In thisinstance, the structure is essentially the same as shown in Fig. 4,except that the plates 88 of the former figure have been replaced byplates I8 having considerable less thickness than the plates 84 Theimproved performance is attributed to the fact that the gases generatedby the arc playing on the adiacent portions of insulating material areat a rela-' tiveiy high temperature. When these hot gases enter thespaces between the relatively cool lates heat from the gases firstgenerated by the direct action of the arc. It will, of course, beunderstood that either of the structures shown in Fig.v

4 or Fig. 5 may utilize a filling in member or plunger 88 havingcircumferentially disposed grooves 82 as shown in Fig. 6, with all theattending advantages of such a plunger.

' It will also be understood that either the plunger 48 or the plunger88 may be provided with an iron core 18 as specifically illustrated inFig. 7. The use of an iron core 18 in the plunger strengthens the radialmagnetic field set up by the coil 88 so as to obtain more positiverotation of the arc about the annular arc passage.

The principles of my invention may also be applied to a structure of thetype illustrated in Fig. 8. As shown in this figure, the arc passage ofthe interrupting unit .is formed by a plurality of plates 88 ofinsulating material having alined openings therethrough of diameterslightly greater than the outside diameter of the tubular movablecontact 28. The plates 88 are held in spaced relation with respect toeach other by means of annular spacing members 82. The

.entire assembly is clamped between upper and lower end plates 84 and86, respectively. Instead of employing a movable plunger or fillingmember, a fixed filling member 88 of insulating material is suspendedfrom the upper plate 84. The filling member 88 has an outside diameterwhich is substantially equal to the inside diameter of the tubularcontact 28. The tubular contact 28 in this instance engages a fixedcontact 88 disposed between the upper plate 84 and an annular arcingplate 82. A radial field coil 84 is also employed having its respectiveends connected between the upper plate 8| and the arcing plate 82. Inthis instance, escape of the gas from the arc passage resulting fromdraw- I v ing an are within the space between the plates 88 and thefilling member '88 is provided by a pluralityof vent openings 88extending radially through an annular plate 88 adjacent the arcing plate82. The plate immediately below the venting plate 88 shown at I88, is ofconsiderably greater thickness than the plates 88 for the purpose ofincreasing the mechanicalstrength of the structure in order to enablethe structure to withstand the pressure created within the arc passage.The upper portion of the plate I88 is so beveled as to provide anunimpeded flow of gas to the vent openings 86.

It will be observed that as the arc is drawn into the narrow arc passageformed between the side walls of the apertures in plates 88 and thefilling member 88, a considerable quantity of gas is generated whichis'stored in the spaces :between the plates 88 during the high values ofinstantaneous arc current. At or near current zero, when pressure in thearc passage has been materially lowered, the flow of gas is reversed andpasses into the arc passage through the are stream and finally throughthe vent openings 88.

Although I have shown the filling member 88 as comprising insulatingmaterial throughout, it

radial magnetic field across the annular are passage. It will also beunderstood that the specific description and illustrations of thevarious cmbodiments of my invention are merely for the purpose ofillustration and that changes and modifications may be made by thoseskilled in the art without departing from the spirit and scope of theappended claims.

' Iclaim as my invention:

1. In a. circuit interrupter, means of insulating material defining anarc chamber, a pair of contacts at least one of which is movable and hasa passage therethrough, means for actuating said contacts to the openposition for establishing an are within said chamber, and means at leastpartially of insulating material normally outside oi said are chamberand movable into said chamber during the circuit opening operation forrestricting the cross section thereof, the walls of said chamberproducing a gas when acted upon by an arc, said means movable into saidchamber substantially closing one end of said chamber for causing saidgas to be expelled from said chamber through the arc path and throughthe passage in said one contact.

2. In a circuit intemipter, means of insulating material defining an arcchamber, a pair oi contacts at least one oi which is movable and has apassage therethrough, means for actuating said contacts to the openposition for establishing an are within said chamber, and a plunger atleast partially of insulating material movable with said one contactinto said arc chamber to restrict the cross section of the same duringthe circuit opening operation, said plunger substantially closing oneend of said are chamber but providing a tree passage for the expulsionoi the products or decomposition of said are from said are chamberthrough the arc path and said passage in said one contact.

3. In a circuit interrupter, means of insulating material defining anarc chamber open at both ends, a gas receiving chamber communicatingwith one end of said are chamber, a fixed contact at the other end ofsaid are chamber, a cooperating tubular contact normally substantiallyfilling said are chamber, means for moving said tubular contact toestablish an arc within said arc chamber, and a plunger movable withsaid tubular contact into said are chamber, said plunger substantiallyclosing said other end of said are chamber to cause gas produced by saidarc to be expelled from the arc chamber through said tubular contactinto the gas receiving chamber.

4. In a circuit interrupter, means 01' insulating material defining anarc chamber open at both ends, a gas receiving chamber communicatingwith one end of said arc chamber, a fixed contact at the other end ofsaid are chamber, a cooperating tubular contact normally substantiallyfilling said are chamber, operating means within said gas receivingchamber for actuating said tubular contact to establish an are withinsaid arc chamber, and a plunger adapted to be moved into said arechamber in response to movement of said tubular contact, said plungersubstantially closing said other end oi said are chamber to cause gasproduced by said are to be expelled from the arc chamber through saidtubular contact into the gas receiving chamber.

5. In a circuit interrupter, means of insulating material defining anarc passage, means for establishing an arc within said passage, fillingmeans at least partially of insulating material normally outside of saidpassage and movable into said passage upon the establishment of saidarc,

and means for rotating said are in the space 78 between the walls ofsaid passage and said movable filling means.

6. In a circuit interrupter, means of insulating material defining acylindrical arc passage, means for establishing an are within saidpassage. a cylindrical plunger at least partially of insulating materialmovable into said are passage upon the establishment 01' said are toprovide an annular arc path, and means for setting up a radial magneticfield across said annular arc path for rotating the arc therearound.

7. In a circuit interrupter, means of insulating material defining acylindrical arc chamber open at least at one end, a fixed contactadjacent one end of said chamber, a cooperating tubular contact normallysubstantially filling said chamber and movable through the open endthereof, means for operating said tubular contact to the open pomtion toestablish an are within said chamber, a plunger at least partially oiinsulating material movable with said tubular contact into said arechamber to provide a generally annular arc path, and means for rotatingthe are around said are path, said plunger causing the gas produced bythe action of the arc to be expelled from said arc chamber through saidtubular contact.

8. In a circuit interrupter, means of insulating material defining acylindrical arc chamber open at least at one end, a fixed contactadjacent one end of said chamber, a cooperating tubular contact normallysubstantially filling said chamber and movable through the open endthereof, means for operating said tubular contact to the open positionto establish an are within said chamber, a plunger at least partially ofinsulating material movable with said tubular contact into said arechamber to provide a generally annular arc path, and means for rotatingthe are around said arc path, and a gas receiving chamber adjacent theopen end .of said are chamber and into which said tubular contact ismovable, said plunger causing the gas produced by the action of the arcto be expelled from said are chamber through said tubular contact intosaid gas receiving chamber.

9. In a circuit interrupter for alternating current, means of insulatingmaterial defining an arc passage, means for establishing an are withinsaid passage, at least a portion of the walls 01' said passage producinga gas when acted upon by an arc to aid in extinguishing the arc, and aplunger at least partially of insulating material movable into saidpassage upon the establishment 01' said arc, said plunger having aplurality of recesses for the storage of gas during high values ofinstantaneous current in the cycle, said gas stored in said recessesbeing discharged into the arc stream as the current passes through zero.

10. In a circuit interrupter for alternating current, means 01'insulating material defining an arc passage, a fixed contact adjacentone end of said arc passage, a cooperating tubular contact normallysubstantially filling sai are p sage, means for moving said tubularcontact through said passage to establish an arc therein, and a groovedplunger at least partially of insulating material movable with saidtubular contact into said are passage, the walls of said are passage andsaid plunger producing a gas when acted upon by said are, said plungerbeing spaced from one end of said tubular contact to cause said gas tobe expelled from said are passage through the arc stream and throughsaid tubular contact.

11. In a circuit interrupter, means or insulating material defining acylindrical arc passage, means for establishing an are within said,passage. a cylindrical plunger at least partially of insulating materialmovable into said are passage upon the establishment of said are toprovide an annular arc path, and means for setting up a radial magneticfield across said annular arc-path for rotating the arc therearound.said plunger having a core of magnetic material for producing a moreuniform distribution of magnetic flux across said annular arc path.

12. In a circuit interrupter, means of insulating material defining acylindrical arc chamber, a fixed contact adjacent one end of saidchamber, a movable contact cooperating'with said fixed contact andmovable through said are chamber to establish an arc therein, a groovedcylindrical plunger at least partially of'insulating material movableinto said are chamber upon the formation of an arc therein to provide agenerally annular arc path, and means for setting up a radial magneticfield across said are path for rotating the arc therearound. saidplunger having a core of magnetic material for producing a more uniformdistribution of magnetic flux across said annular arc path.

13. In a circuit interrupter, an arc extinguishing device includingmeans of insulating material having an opening therethrough, means forestablishing an are within said opening, a filling member of insulatingmaterialmovable into said opening to restrict the cross section thereof,and a plurality of pockets positioned along said opening for receivinggas produced by the action of said are upon said insulating material,said pockets being of sumcient depth so that at least a relatively largeportion of said gas is stored in said pockets during the high values ofinstantaneous current and expe d through the arc stream as the arccurrent passes through zero.

14. In a circuit interrupter, an arc extinguishing device including aplurality of plates of insulating material having aligned openingstherethrough to define an are c, said plates being spaced from eachother to provide pockets alon said passage, said pockets being closed onall sides except the side leading to said passage, means forestablishing an are within said passage, and a' plunger at leastpartially of insulating material normally outside said e movable intosaid passage upon the formation of said arc,'said plates and saidplunger producing a gas when acted upon by an arc, and said pocketsbeing relatively deep so that a relatively large quantity of gas isstored in said pockets during the high values of instantaneous arccurrent and discharged through the arc stream as the are current passesthrough zero. I

15. In a circuit interrupter, an arc extinguishing device including aplurality of plates of insulating material having aligned openingstherethrough 'to define an arc passage, said plates being spaced fromeach other to provide pockets along said passage, said pockets beingclosed on all sides except the side leading to said passage, a fixedcontact adjacent one end of said passage, a cooperating tubular contactnormally substantially filling said are passage, means for moving saidtubular contact through said passage to establish an arc therein, and afilling member at least partially of insulating material movable withsaid tubular contact into said are passage, said plates producing a gaswhen acted upon by. an arc, which gas is retained in said pockets duringpredetermined pressure conditions in said are e andexpelled intothe arcpassage in accordance with the pressure conditions therein, said fillingmember causing the gas to fiow from said passage through the arc streamand through said tubular contact.

18. In a circuit interrupter, an arc extinguishing device including aplurality of plates of insulating material having openings therethroughto provide an arc w e, means spacing said plates from each other toprovide gas receiving chambers along said are means for establishing anare within said p, said plates of insulating material producing a gaswhen acted upon by an are, at least a portion of said gas being storedin said gas receiving bers during high values of instantaneous arccurrent, said gas being returned to said are passage when the arccurrent through zero, a

means disposed within said gas receiving chambers for cooling the gastherein, and means mov. able into said are passage for directing saidgas through the arc stream when it is expelled from said passage.

. 1'1. In a circuit interrupter, an arc extinguishing device including aplurality of plates or insulating material having openings therethroughto provide an arc passage, means spacing said plates from each other toprovide gas receiving chambers along said are passage, a fixed contactadjacent one end of said are passage, 'a cooperating tubular contactnormally within said are passage and movable therethrough to establishan arc therein, said plates of insulating material producing a gas whenacted upon by an are, at least a portion of said gas being stored insaid gas receiving chambers during predetermined pressure conditionswithin said are passage and returnable to said are passage during otherpredetermined pressure conditions in said e, plates of metallic materialdisposed in said gas receiving chambers for cooling the gas therein, anda plunger movable with said tubuluar contact into said are passage forcausing gas to be expelled from said passage through the arc stream andsaid tubular contact.

18. In a circuit interrupter, an arc extinguishing device includingmeans of insulating material having an opening therethrough, means forestablishing an are within said opening, a filling member of insulatingmaterial movable into said opening to restrict the cross section thereofand accordance with predetermined pressure conditions in said opening.

19. In a circuit interrupter, an arc extinguishing device including aplurality of plates of insulating material having openings therethroughto provide an arc passage, a fixed contact adjacent one end of said arepassage, a cooperating tubular contact normally substantially fillingsaid are passage and movable therethrough to establish an arc therein, aplunger movable into said are passage upon the formation of an arctherein to provide a narrow generally annula'r arc path, and means forsetting up a radial magnetic field across said annular arc path forrotating the arc therearound.

20. In a circuit interrupter, an arc extinguishing device includingmeans of insulating material having an opening therethrough, a fillingmember at least partially of insulating material extending into saidopening to provide a narrow generally annular arc passage, a fixedcontact adjacent one end of said arc passage, a cooperating tubularcontact normally surrounding said filling member and substantiallyfilling said annular arc passage, means for, moving said tubular contactto establish an are within said arc passage, said means of insulatingmaterial having a plurality oi! recesses positioned along said openingfor receiving gas produced by the action of said are upon saidinsulating material and venting means disposed to cause gas produced bythe action of the are upon said means of insulating material and saidfilling member to be expelled from said recesses and said arc passagethrough the arc stream in a direction opposite to the opening movementoi said tubular contact.

21. In a circuit interrupter, an arc extinguishing device including aplurality oi plates of insulating material having openings therethrough,a filling member at least partially of insulating material extendinginto said openings to provide a narrow generally annular arc passage, afixed contact adjacent one end of said are passage, a cooperatingtubular contact normally surrounding said filling member andsubstantially filling said annular arc passage, means for moving saidtubular contact to establish an are within said are passage, means forrotating the are around said annular arc passage, and means spacing saidplates from each other to provide a plurality of chambers along said arepassage for receiving gas produced by the action of said arc upon saidplates and said filling member, at least a portion of said gas beingcollected in said chambers and expelled through the arc stream inaccordance with predetermined pressure conditions in said arc passage.

22. In a circuit interrupter, an arc extinguishing device including aplurality of plates oi gasevolving material having aligned openingstherethrough to define an arc passage, said plates being spaced fromeach other to provide deep pockets along said passage, said pocketsbeing closed on all sides except the side leading to said passage, meansfor establishing an are within said passage, and a plunger at leastpartially of insulating material normally outside said passage movableinto said passage upon the formation of said are, said plates and saidplunger producing an arc extinguishing gas when acted upon by the arc,at least a considerable portion of said gas produced during the highvalues of instantaneous arc current filling said pockets and reactingupon said plates to produce an additional quantity of arc extinguishinggas, a substantial portion of said gas thus produced being dischargedthrough the arc stream as the arc current passes through zero.

23. In an alternating-current circuit interrupter of the gas blast type,means at least partially of insulating material for defining the arcpassage in which an arc is adapted to play, said passage having aplurality of deep recesses therealong, the walls of saidpassage'including said recesses having gas evolving surfaces, theportions of said are passage between adjacent recesses evolving an arcextinguishing gas when acted upon by an arc, the walls of said recessesproviding storage and cooling spaces for said gas and an additional gasgenerating source during the peak oi. the current wave, said recessesbeing so disposed with respect to said arc passage that at the time oflow pressure near current zero in said passage at least a portion 01 thegas stored. generated and cooled in said recesses will fiow through thesaid are passage.

24. In a circuit interrupter, means at least partially of insulatingmaterial defining an arc chamber having an exhaust opening, arcing meansin said chamber for establishing a section of arc which is adapted toplay opposite said opening and another section of are being moreconfined for generating arc pressure in said chamber for causing a blastof gas through said exhaust opening and said first section of arc, andchamber means within said are chamber and extended beyond the arc pathfor the fiow of arc gases therein out of the arc path, and cooling meansin said chamber means including material adapted to emit an arcextinguishing gas when subjected to the arc heat and the hot gases fromsaid more confined section of arc.

25. In a circuit interrupter, means at least partially of insulatingmaterial defining an arc.

chamber having an exhaust opening, contact means for establishing an arcwithin said chamber, one section of said are being located substantiallyopposite said exhaust opening so that gas in exhausting from saidchamber is confined to a high velocity path directly traversing saidare, another section of are being more remotely located in said chamberfor generating pressure, and cooling structure within said chamberincluding a plurality of spaced plate members between which the hot arcgases from said remotely positioned arc section are adapted to fiow to aposition between said plates out 01 the path of said arc, said platemembers presenting a large cooling suriace to said gas and being in partcomposed of a material which emits an arc-extinguishing gas whensubjected to the heat of the arc and the arc gases.

26. In a circuit interrupter, means at least par tially of insulatingmaterial defining an arc chamber having an exhaust opening, means forestablishing an arc in said chamber, cooling structure along the path oisaid are within said chamber into which the are gases are adapted toflow, said cooling structure extending beyond the path of said are andincluding material which emits arc-extinguishing gas when acted upon bythe heat of the arc and are gases, and means movable along the arc pathfor directing the arc-extinguishing gas through the arc stream and saidexhaust opening.

27. In a circuit interrupter, means at least partially of insulating.material defining an arc chamber having an exhaust opening, arcing meansin said chamber for establishing a section 0! arc which is adapted toplay opposite said opening and another section of are being moreconfined for generating arc pressure in said chamber for causing a blastof gas through said exhaust openingand said first section of arc,

- and chamber means within said are chamber and extended beyond the arcpath for the fiow of arc gases therein out of the arc path, and coolingmeans in said chamber means including material adapted to emit an arcextinguishing gas when subjected to the are heat and the hot gases fromsaid more confined section 01 are, and

metallic cooling means.

. :m- :m' L. RAWLINS.

